Lead-acid batteries (lead battery) are standard on most types of vehicles. In particular, lead batteries are used to start the internal combustion engines of automobiles, trucks and other types of vehicles and equipment. Most of the vehicles and equipment that use lead batteries for starting are operated on a regular, e.g., daily, basis. However, some vehicles with lead batteries operate only seasonally. For example, lead batteries are used to start the internal combustion engines of off-road vehicles, recreational vehicles (RV), lawn tractors, snow mobiles, agricultural equipment, construction equipment, military vehicles and boats, all of which may be left idle for months at a time during off-season periods. This invention pertains to lead-acid batteries for use with seasonally operated vehicles and equipment.
Lead-acid batteries are principally used in vehicles and equipment to provide electrical current to power electric motors to crank start the engine. In addition, lead-acid batteries supply electricity for lighting and ignition applications in vehicles and equipment. These battery requirements are colloquially known in the battery industry as SLI (Starting, Lighting, and Ignition) requirements. For SLI applications, it is well-known that lead acid batteries enjoy the best price/performance ratio for all energy storage devices available on the market today.
The demands placed on a battery may vary widely based on consumer habits, equipment usage, maintenance schedules, and other factors. The batteries must be designed and selected to satisfy these varying demands. Moreover, seasonal usage of a battery places especially difficult demands on a battery. Lead-acid batteries in seasonal and off-road vehicles and equipment may sit idle and unused for up to 11 out of 12 months of the year. This limited usage may continue year-after-year. Conventional lead batteries very often discharge and deteriorate over long idle periods, to such an extend that the batteries cannot start an engine when desired. For example, home consumers find a dead battery all to common and irritating in their recreational vehicles and lawn tractors, when they first start their vehicles, e.g, in the Spring, after the vehicles have sat idle for months. Accordingly, there has been a long-felt need for a battery that will allow a home user to start seasonal vehicles and equipment at the beginning of each season, year-after-year. Similar a long felt needs exist for all seasonally or intermittently operated equipment and vehicles that rely on a lead-acid battery for starting. For example, the need has long existed for a battery that can start a long-idled diesel engine, since diesel engines are particularly troublesome to start. It has proven especially difficult to fabricate a lead-acid battery for SLI applications that can satisfy the demands of starting an internal combustion engine after a long idle period.
Extended idle periods are detrimental to lead-acid batteries. Batteries are wet, active devices that self-discharge even when idle. Moreover, some vehicles and equipment place parasitic loads, e.g., clocks, security sensors and computer controllers, on the battery that continue to drain the battery for the months while the vehicle remains idle. Over the course of several months, these parasitic loads in combination with the natural self-discharge of a battery can place the battery in a extremely discharged state. As they discharge, the batteries gradually lose their capacity to provide current and power to start an engine. While batteries can be recharged, most engine alternators are not designed to provide the voltages and currents required to completely recharge a dead battery.
In addition, lead sulfate (PbSO.sub.4) crystals on the plates are formed as batteries discharge. These crystals become relatively difficult to charge if left uncharged for many months. Moreover, the fluid in a battery tends to evaporate during months of idle time to such an extend that the top edges of the battery plates become exposed and are susceptible to corrosion. This corrosion of plates, especially positive plates, further deteriorates the ability of a battery to be recharged and hold a charge. Accordingly, conventional lead-acid batteries present long-unsolved problems that result when the battery sits idle for an extended period, such as occurs in vehicles and equipment that are only used seasonally.
The current invention overcomes the problems of prior art batteries that were due to long periods of idleness. It is an objective of this invention to overcome two major problems associated with long-idled batteries by applying battery design features that protect the battery from permanent deep discharge damage, and promotes charge acceptance after long idle periods. These long-felt problems have been overcome by a unique combination of battery materials that are applied in unique proportions that have been found by experimentation to enable the battery to better hold a charge during long idle periods. While most of the individual battery materials used in this invention are common to prior-art lead acid batteries, the proportions and ratio at which these well-known materials are applied are unique and heretofore unknown. The common materials which are used in certain unique concentrations and proportional amounts, include as the most prominent materials lead and acid. By maintaining a unique ratio of lead and acid concentrations, a battery has been invented that exhibits superior performance after long periods of idleness.
This invention also uses certain materials and/or material characteristics that are unique either in their use or in their amount. These materials relate to the negative grid metal alloy, positive grid metal alloy, negative leady oxide paste-mix formulation, positive leady oxide paste mix formulation, separator material type, sulfuric acid electrolyte, and a sulfuric acid electrolyte additive. The optimal materials and their proportions and ratios of use are disclosed in detail in the body of this specification. These unique materials and the conventional materials, used in unique proportions and percentages, have by experimentation been found to provide cumulatively an advantageous lead acid battery that is well-suited for seasonal use and overcomes many of the long-felt problems that have plagued lead-acid batteries in the past.